The present invention concerns a sensor for electric measurement of positive and negative expansion of cylindrical bodies.
Expansion sensors are known which by means of a cylindrical elastic body press expansion measurement strips onto the surface of a drilled hole and measure the expansion of the hole surface directly by friction force and thus can measure the stresses in cylindrical bodies.
Other systems used today have measurement bridges, with blades with constant spacing held by belts or magnets against the surface of cylindrical bodies, and thus measure the expansion occurring.
The first expansion sensors above have the disadvantage that a hole must be drilled. The second solution explained above is very exposed, slips easily and is therefore not suitable for industrial use.